Current State of Evidence: Influence of Nutritional and Nutrigenetic Factors on Immunity in the COVID-19 Pandemic Framework.

The pandemic caused by the new coronavirus has caused shock waves in many countries, producing a global health crisis worldwide. Lack of knowledge of the biological mechanisms of viruses, plus the absence of effective treatments against the disease (COVID-19) and/or vaccines have pulled factors that can compromise the proper functioning of the immune system to fight against infectious diseases into the spotlight. The optimal status of specific nutrients is considered crucial to keeping immune components within their normal activity, helping to avoid and overcome infections. Specifically, the European Food Safety Authority (EFSA) evaluated and deems six vitamins (D, A, C, Folate, B6, B12) and four minerals (zinc, iron, copper and selenium) to be essential for the normal functioning of the immune system, due to the scientific evidence collected so far. In this report, an update on the evidence of the contribution of nutritional factors as immune-enhancing aspects, factors that could reduce their bioavailability, and the role of the optimal status of these nutrients within the COVID-19 pandemic context was carried out. First, a non-systematic review of the current state of knowledge regarding the impact of an optimal nutritional status of these nutrients on the proper functioning of the immune system as well as their potential role in COVID-19 prevention/treatment was carried out by searching for available scientific evidence in PubMed and LitCovid databases. Second, a compilation from published sources and an analysis of nutritional data from 10 European countries was performed, and the relationship between country nutritional status and epidemiological COVID-19 data (available in the Worldometers database) was evaluated following an ecological study design. Furthermore, the potential effect of genetics was considered through the selection of genetic variants previously identified in Genome-Wide Association studies (GWAs) as influencing the nutritional status of these 10 considered nutrients. Therefore, access to genetic information in accessible databases (1000genomes, by Ensembl) of individuals from European populations enabled an approximation that countries might present a greater risk of suboptimal status of the nutrients studied. Results from the review approach show the importance of maintaining a correct nutritional status of these 10 nutrients analyzed for the health of the immune system, highlighting the importance of Vitamin D and iron in the context of COVID-19. Besides, the ecological study demonstrates that intake levels of relevant micronutrients-especially Vitamins D, C, B12, and iron-are inversely associated with higher COVID-19 incidence and/or mortality, particularly in populations genetically predisposed to show lower micronutrient status. In conclusion, nutrigenetic data provided by joint assessment of 10 essential nutrients for the functioning of the immune system and of the genetic factors that can limit their bioavailability can be a fundamental tool to help strengthen the immune system of individuals and prepare populations to fight against infectious diseases such as COVID-19.

Biomarkers of Nutrition and Health: New Tools for New Approaches.

A main challenge in nutritional studies is the valid and reliable assessment of food intake, as well as its effects on the body. Generally, food intake measurement is based on self-reported dietary intake questionnaires, which have inherent limitations. They can be overcome by the use of biomarkers, capable of objectively assessing food consumption without the bias of self-reported dietary assessment. Another major goal is to determine the biological effects of foods and their impact on health. Systems analysis of dynamic responses may help to identify biomarkers indicative of intake and effects on the body at the same time, possibly in relation to individuals' health/disease states. Such biomarkers could be used to quantify intake and validate intake questionnaires, analyse physiological or pathological responses to certain food components or diets, identify persons with specific dietary deficiency, provide information on inter-individual variations or help to formulate personalized dietary recommendations to achieve optimal health for particular phenotypes, currently referred as "precision nutrition." In this regard, holistic approaches using global analysis methods (omics approaches), capable of gathering high amounts of data, appear to be very useful to identify new biomarkers and to enhance our understanding of the role of food in health and disease.

Vitamin E Metabolic Effects and Genetic Variants: A Challenge for Precision Nutrition in Obesity and Associated Disturbances.

Vitamin E (VE) has a recognized leading role as a contributor to the protection of cell constituents from oxidative damage. However, evidence suggests that the health benefits of VE go far beyond that of an antioxidant acting in lipophilic environments. In humans, VE is channeled toward pathways dealing with lipoproteins and cholesterol, underlining its relevance in lipid handling and metabolism. In this context, both VE intake and status may be relevant in physiopathological conditions associated with disturbances in lipid metabolism or concomitant with oxidative stress, such as obesity. However, dietary reference values for VE in obese populations have not yet been defined, and VE supplementation trials show contradictory results. Therefore, a better understanding of the role of genetic variants in genes involved in VE metabolism may be crucial to exert dietary recommendations with a higher degree of precision. In particular, genetic variability should be taken into account in targets concerning VE bioavailability per se or concomitant with impaired lipoprotein transport. Genetic variants associated with impaired VE liver balance, and the handling/resolution of oxidative stress might also be relevant, but the core information that exists at present is insufficient to deliver precise recommendations.

Gender-Associated Impact of Early Leucine Supplementation on Adult Predisposition to Obesity in Rats.

Early nutrition plays an important role in development and may constitute a relevant contributor to the onset of obesity in adulthood. The aim of this study was to evaluate the long-term impact of maternal leucine (Leu) supplementation during lactation on progeny in rats. A chow diet, supplemented with 2% Leu, was supplied during lactation (21 days) and, from weaning onwards, was replaced by a standard chow diet. Then, at adulthood (6 months of age), this was replaced with hypercaloric diets (either with high-fat (HF) or high-carbohydrate (HC) content), for two months, to induce obesity. Female offspring from Leu-supplemented dams showed higher increases in body weight and in body fat (62%) than their respective controls; whereas males were somehow protected (15% less fat than the corresponding controls). This profile in Leu-females was associated with altered neuronal architecture at the paraventricular nucleus (PVN), involving neuropeptide Y (NPY) fibers and impaired expression of neuropeptides and factors of the mTOR signaling pathway in the hypothalamus. Interestingly, leptin and adiponectin expression in adipose tissue at weaning and at the time before the onset of obesity could be defined as early biomarkers of metabolic disturbance, predisposing towards adult obesity under the appropriate environment.

Methylation analysis in fatty-acid-related genes reveals their plasticity associated with conjugated linoleic acid and calcium supplementation in adult mice.

PURPOSE: DNA methylation is one of the most extensively studied mechanisms within epigenetics, and it is suggested that diet-induced changes in methylation status could be involved in energy metabolism regulation. Conjugated linoleic acid (CLA) and calcium supplementation counteract body weight gain, particularly under a high-fat (HF) diet, in adult mice. The aim was to determine whether the modulation of DNA methylation pattern in target genes and tissues could be an underlying mechanism of action. METHODS: Mice (C57BL/6J) were divided into five groups according to diet and treatment: normal fat as the control group (12 % kJ content as fat), HF group (43 % kJ content as fat), HF + CLA (6 mg CLA/day), HF + calcium (12 g/kg of calcium) and HF with both compounds. Gene expression and methylation degree of CpG sites in promoter sequences of genes involved in fatty acid metabolism, including adiponectin (Adipoq), stearoyl-CoA desaturase (Scd1) and fatty acid synthase (Fasn), were determined by bisulphite sequencing in liver and epididymal white adipose tissue. RESULTS: Results showed that the methylation profile of promoters was significantly altered by dietary supplementation in a gene- and tissue-specific manner, whereas only slight changes were observed in the HF group. Furthermore, changes in specific CpG sites were also associated with an overall healthier metabolic profile, in particular for calcium-receiving groups. CONCLUSIONS: Both CLA and calcium were able to modify the methylation pattern of genes involved in energy balance in adulthood, which opens a novel area for increasing efficiency in body weight management strategies.

Calcium supplementation modulates gut microbiota in a prebiotic manner in dietary obese mice.

SCOPE: Dietary calcium has been inversely associated with body fat and energy balance. The main scope of this study has been to assess the potential contribution of gut microbiota on energy regulation mediated by calcium. METHODS AND RESULTS: Gut microbiota in C57BL/6J mice receiving calcium supplementation under a high-fat (HF) diet were analysed by PCR and their relationships with host metabolic parameters were determined. Calcium conferred a prebiotic-like effect on gut microbiota, and animals presented lower plasmatic endotoxin levels, increased expression of angiopoietin-like 4 in intestine and lower hepatic lipid content, although increased expression of stress markers in adipose tissue and of inflammation in liver was also found. To determine whether slimming effects could be transferred to obese mice, a faecal microbial transplant (FMT) was carried out, showing that host bacteria grown under a HF diet could not be superseded by those from calcium-fed animals. Therefore, FMT was not able to transfer the beneficial effects of calcium. CONCLUSION: In conclusion, calcium modulated gut microbiota in a prebiotic manner, establishing a host cross-talk and promoting a healthier metabolic profile. However, lack of effectiveness of FMT suggests the need of further appropriate dietary factors in addition to the bacteria per se.

Body fat loss induced by calcium in co-supplementation with conjugated linoleic acid is associated with increased expression of bone formation genes in adult mice.

The potential of conjugated linoleic acids (CLA) and calcium in weight management in animal models and human studies has been outlined, as well as their use to prevent bone loss at critical stages. In addition, it has been suggested that bone remodeling and energy metabolism are regulated by shared pathways and involve common hormones such as leptin. We have previously shown that supplementation with CLA and calcium in adult obese mice decreases body weight and body fat. The aim of the present study was to assess the effects of these two compounds on bone and energy metabolism markers on bone. Mice (C57BL/6J) were divided into five groups according to diet and treatment (up to 56 days): control (C), high-fat diet (HF), HF+CLA (CLA), HF+calcium (Ca) and HF with both compounds (CLA+Ca). At the end of treatment, bone formation markers were determined in plasma and expression of selected bone and energy markers was determined in tibia by quantitative polymerase chain reaction. Results show that CLA was associated with decreased tibia weight and minor impact on bone markers, whereas calcium, either alone or co-supplemented with CLA, maintained bone weight and promoted the expression of bone formation genes such as bone gamma-carboxyglutamate protein 2 (Bglap2) and collagen Iα1 (Col1a1). Furthermore, it had a significant effect on key players in energy metabolism, in particular leptin and adiponectin tibia receptors. Overall, in addition to the weight loss promoting properties of calcium, on its own or co-supplemented with CLA, our results support beneficial effects on bone metabolism in mice.

Conjugated Linoleic Acid Supplementation under a High-Fat Diet Modulates Stomach Protein Expression and Intestinal Microbiota in Adult Mice.

The gastrointestinal tract constitutes a physiological interface integrating nutrient and microbiota-host metabolism. Conjugated linoleic acids (CLA) have been reported to contribute to decreased body weight and fat accretion. The modulation by dietary CLA of stomach proteins related to energy homeostasis or microbiota may be involved, although this has not been previously analysed. This is examined in the present study, which aims to underline the potential mechanisms of CLA which contribute to body weight regulation. Adult mice were fed either a normal fat (NF, 12% kJ content as fat) or a high-fat (HF, 43% kJ content as fat) diet. In the latter case, half of the animals received daily oral supplementation of CLA. Expression and content of stomach proteins and specific bacterial populations from caecum were analysed. CLA supplementation was associated with an increase in stomach protein expression, and exerted a prebiotic action on both Bacteroidetes/Prevotella and Akkermansia muciniphila. However, CLA supplementation was not able to override the negative effects of HF diet on Bifidobacterium spp., which was decreased in both HF and HF+CLA groups. Our data show that CLA are able to modulate stomach protein expression and exert a prebiotic effect on specific gut bacterial species.

Effects of milk supplementation with conjugated linoleic acidon weight control and body composition in healthy overweight people / Efecto de una suplementación láctea con ácido linoleico conjugado sobre el control de peso y la composición corporal de personas sanas con sobrepeso

Introduction: Conjugated linoleic acids (CLAs) have shown beneficial effects in weight control therapy however this relation is not clear. Objetive: The aim of the study was to examine the effects and safety of 3 g of a 1:1 mix of c9-t11 and t10-c12 on weight control and body composition in healthy overweight individuals. Methods: A prospective, placebo-controlled, randomised double-blind, parallel clinical trial lasting 24 weeks was carried out in 38 volunteers (29w, 9m) aged 30-55 years and BMI ≥ 27 -<30 kg/m2 who consumed 200 ml/day of skimmed milk with 3g of CLAs or 3g olive oil (placebo). Anthropometric, biochemical and dual x-ray absorptiometry (DXA) tests were measured. Diet and physical activity were assessed. Results: Subjects maintained their habitual dietary and exercise patterns over the study. Only CLA group showed a significant decrease in weight (74.43 ± 10.45 vs 73.54 ± 11.66 kg, p = 0.029) and waist circumference (91.45 ± 10.33 vs 90.65 ± 9.84 cm, p = 0.012) between baseline and end of the study. BMI and waist height ratio decreased (28.44 ± 1.08 vs 27.81 ± 1.43 kg/m2, p = 0.030 and 0.57 ± 0.05 vs 0.56 ± 0.04 p = 0.013 respectively) in CLA group at the end. CLA group experienced a reduction in total fat mass after 24 weeks (38.62 ± 5.02 vs 36.65 ± 5.64%, p = 0.035). No decrease was observed in Control group. HOMA index had no changes. Conclusions: The consumption of skimmed milk enriched with 3g of a 1:1 mixture of c9-t11 and t10-c12 for 24 weeks led to a decrease in body weight and total fat mass in healthy, overweight subjects who maintained habitual diets and exercise patterns. No adverse effects were observed. Registered under ClinicalTrials.gov Identifier No. NCT01503047 (AU)

Introducción: Los ácidos linoleicos conjugados (ALC) han mostrado unos efectos beneficiosos en el tratamiento del control de peso; sin embargo, esta relación no está clara. Objetivo: El propósito de este estudio fue examinar los efectos y la seguridad de 3 g de una mezcla 1:1 de c9-t11 y t10-c12 sobre el control de peso y la composición corporal en individuos sanos con sobrepeso. Métodos: Se realizó un estudio clínico prospectivo, de grupos paralelos, de distribución aleatoria, a doble ciego y con control placebo, de 24 semanas de duración, en 38 voluntarios (29 mujeres, 9 hombres) con edades de 30-55 años y un IMC ≥ 27 -< 30 kg/m2 que consumieron 200 ml/día de leche desnatada con 3 g de ALC o 3 g de aceite de oliva (placebo). Se midieron datos de antropometría, bioquímica y absorciometría dual de rayos X (DXA). Se evaluaron la dieta y la actividad física. Resultados: Los sujetos mantuvieron sus patrones habituales de dieta y ejercicio a lo largo del estudio. Sólo el grupo de ALC mostró una reducción significativa del peso (74,43 ± 10,45 vs 73,54 ± 11,66 kg, p = 0,029) y de la circunferencia de la cintura (91,45 ± 10,33 vs 90,65 ± 9,84 cm, p = 0,012) entre el periodo basal y el final del estudio. El IMC y el cociente cintura/talla disminuyeron (28,44 ± 1,08 vs 27,81 ± 1,43 kg/m2, p = 0,030 y 0,57 ± 0,05 vs 0,56 ± 0,04 p = 0,013, respectivamente) en el grupo ALC al final del estudio. El grupo ALC experimentó una reducción de la masa grasa total tras 24 semanas (38,62 ± 5,02 vs 36,65 ± 5,64 %, p = 0,035). No se observó reducción en el grupo control. El índice HOMA no experimentó cambios. Conclusiones: El consumo de leche desnatada enriquecida con 3 g de una mezcla 1:1 de c9-t11 y t10-c12 durante 24 semanas produjo un descenso del peso corporal y la masa grasa total en sujetos sanos con sobrepeso que mantuvieron sus patrones habituales de dieta y ejercicio físico. No se observaron efectos adversos. Registrado con el identificador núm. NCT01503047 en ClinicalTrials.gov (AU)

Dietary supplementation of calcium may counteract obesity in mice mediated by changes in plasma fatty acids.

The scope of this study was to assess the impact of calcium and conjugated linoleic acid (CLA) supplementation on plasma fatty acid profiles and to evaluate potential synergistic effects of both compounds against dietary obesity. Mice separated into five experimental groups were followed: control (C), high-fat diet (HF), HF with calcium (Ca), HF plus CLA and HF with both Ca and CLA. Plasma metabolites and fatty acids were determined by commercial kits and gas chromatography, respectively. Both dietary calcium and CLA supplementation contributed to lower body fat gain under a HF diet. Maximum efficacy was seen with calcium; no additional effect was associated with the combined treatment with CLA. Plasma leptin, adiponectin and HOMA index were in accordance with an altered glucose/insulin homeostasis in the HF and HF + CLA groups, whereas control levels were attained under Ca-enriched diets. Plasma fatty acids showed minor changes associated to CLA treatment, but a high impact on PUFA was observed under Ca-enriched diets. Our results show that the mechanism underlying the anti-obesity effects of calcium supplementation is mediated mainly by changes in PUFA plasma profile. In addition, the lack of synergy on body weight reduction in combination with associated lipid profiles of calcium and CLA suggests that calcium may interfere with absorption and/or bioactivity of CLA, which can be of relevance when using CLA-fortified dairy products against human obesity.

Effects of milk supplementation with conjugated linoleic acid on weight control and body composition in healthy overweight people.

INTRODUCTION: Conjugated linoleic acids (CLAs) have shown beneficial effects in weight control therapy however this relation is not clear. OBJETIVE: The aim of the study was to examine the effects and safety of 3g of a 1:1 mix of c9-t11 and t10-c12 on weight control and body composition in healthy overweight individuals. METHODS: A prospective, placebo-controlled, randomised double-blind, parallel clinical trial lasting 24 weeks was carried out in 38 volunteers (29w, 9m) aged 30-55 years and BMI ≥27-<30 kg/m2 who consumed 200 ml/day of skimmed milk with 3g of CLAs or 3g olive oil (placebo). Anthropometric, biochemical and dual x-ray absorptiometry (DXA) tests were measured. Diet and physical activity were assessed. RESULTS: Subjects maintained their habitual dietary and exercise patterns over the study. Only CLA group showed a significant decrease in weight (74.43 ± 10.45 vs 73.54 ± 11.66 kg, p = 0.029) and waist circumference (91.45 ± 10.33 vs 90.65 ± 9.84 cm, p = 0.012) between baseline and end of the study. BMI and waist height ratio decreased (28.44 ± 1.08 vs 27.81 ± 1.43 kg/m2, p = 0.030 and 0.57 ± 0.05 vs 0.56 ± 0.04 p = 0.013 respectively) in CLA group at the end. CLA group experienced a reduction in total fat mass after 24 weeks (38.62 ± 5.02 vs 36.65 ± 5.64%, p = 0.035). No decrease was observed in Control group. HOMA index had no changes. CONCLUSIONS: The consumption of skimmed milk enriched with 3g of a 1:1 mixture of c9-t11 and t10-c12 for 24 weeks led to a decrease in body weight and total fat mass in healthy, overweight subjects who maintained habitual diets and exercise patterns. No adverse effects were observed. Registered under ClinicalTrials.gov Identifier No. NCT01503047.

INTRODUCTION: Conjugated linoleic acids (CLAs) have shown beneficial effects in weight control therapy however this relation is not clear. OBJETIVE: The aim of the study was to examine the effects and safety of 3g of a 1:1 mix of c9-t11 and t10-c12 on weight control and body composition in healthy overweight individuals. METHODS: A prospective, placebo-controlled, randomised double-blind, parallel clinical trial lasting 24 weeks was carried out in 38 volunteers (29w, 9m) aged 30-55 years and BMI ¡Ý27-

Expression of adipose microRNAs is sensitive to dietary conjugated linoleic acid treatment in mice.

BACKGROUND: Investigation of microRNAs (miRNAs) in obesity, their genetic targets and influence by dietary modulators is of great interest because it may potentially identify novel pathways involved in this complex metabolic disorder and influence future therapeutic approaches. This study aimed to determine whether miRNAs expression may be influenced by conjugated linoleic acid (CLA), currently used to induce fat loss. METHODOLOGY/PRINCIPAL FINDINGS: We determined retroperitoneal adipose tissue (rWAT) expression of five miRNAs related to adipocyte differentiation (miRNA-143) and lipid metabolism (miRNA-103 and -107) and altered in obesity (miRNA-221 and -222), using the TaqMan®MicroRNA Assay (Applied-Biosystems). In the first experiment, mice were fed with a standard fat diet and orally treated with sunflower oil (control group) and 3 or 10 mg CLA/day for 37 days. In the second experiment, mice were fed with a high fat diet for 65 days. For the first 30 days, mice received the same doses of CLA described above and, from that time onwards, animals received a double dose. Results showed that expression of selected miRNAs was modified in response to CLA treatment and metabolic status. Interestingly, a strong correlation was observed between miR-103 and -107 expression, as well as miR-221 and -222 in both experiments. Moreover, changes in miRNAs expression correlated with several adipocyte gene expressions: miR-103 and -107 correlated with genes involved in fatty acid metabolism whereas miR-221 and miR-222 correlated with the expression of adipocytokines. Regarding the minor changes observed in miR-143 expression, no differences in expression of adipogenic markers were observed. CONCLUSIONS/SIGNIFICANCE: Although elucidating the functional implications of miRNAs is beyond the scope of this study, these findings provide the first evidence that miRNAs expression may be influenced by dietary manipulation, reflecting or even contributing to the new metabolic state originated by CLA treatment.

Moderate doses of conjugated linoleic acid isomers mix contribute to lowering body fat content maintaining insulin sensitivity and a noninflammatory pattern in adipose tissue in mice.

Conjugated linoleic acid (CLA) modulates body composition, especially by reducing adipose tissue. However, despite the increasing knowledge about CLA's beneficial effects on obesity management, the mechanism of action is not yet fully understood. Furthermore, in some human studies fat loss is accompanied by impairment in insulin sensitivity, especially when using the trans-10,cis-12 isomer. The aim of this work was to study the effects of moderate doses of CLA on body fat deposition, cytokine profile and inflammatory markers in mice. Mice were orally treated with a mixture of CLA isomers, cis-9,trans-11 and trans-10,cis-12 (50:50), for 35 days with doses of CLA1 (0.15 g CLA/kg body weight) and CLA2 (0.5 g CLA/kg body weight). CLA had discrete effects on body weight but caused a clear reduction in fat mass (retroperitoneal and mesenteric as the most sensitive depots), although no other tissue weights were affected. Glucose and insulin were not altered by CLA treatment, and maintenance of glucose homeostasis was observed even under insulin overload. The study of gene expression (Emr1, MCP-1, IL-6, TNFalpha, PPARgamma2 and iNOS) either in adipocytes and/or in the stromal vascular fraction indicated that CLA does not lead to the infiltration of macrophages in adipose tissue or to the induction of expression of pro-inflammatory cytokines. The use of a mixture of both isomers, as well as moderate doses of CLA, is able to induce a reduction of fat gain without an impairment of adipose tissue function while preserving insulin sensitivity.

Effect of calcium-enriched high-fat diet on calcium, magnesium and zinc retention in mice.

The aim of this work was to assess the effects of a high-fat diet enriched in Ca, which accompanies lower body fat deposition, on mineral depots, as well as to assess the potential role of adaptive thermogenesis in mice. Male mice were fed ad libitum a high-fat (43 %) diet with a Ca content of 4 g/kg from calcium carbonate (control group) or 12 g/kg (42 % from milk powder and the rest from calcium carbonate) (Ca group) for 56 d. Body weight, food intake and urine were periodically collected. Tissue samples were collected when the mice were killed and the composition was determined. Expression of uncoupling proteins was determined by Western blotting. Mineral content was measured by flame atomic absorption spectrometry. Lower body weight gain and fat accretion was found in the Ca group. This could not be attributable to lower gross energy intake or to activation of adaptive thermogenesis. Although significant urine mineral loss was found in the Ca group, preservation of mineral depots in bone was observed. Our data support the fact that adding more Ca to the diet, using a combination of calcium carbonate plus milk powder containing among other things higher Zn and Mg, contributes to counteracting obesity and improving lipid metabolism.